In U.S. Pat. No. 3,615,956 there is disclosed a gas plasma vapor etching process in which it is possible to perform operations on a wafer formed of a semiconductor material and having a surface capable of carrying at least one layer of at least one different material on the surface and disposed in a chamber having a pressure ranging from one-tenth to 10 mm mercury. Thus, plasma having active halogen species of atoms and molecules is created within a chamber so that the gas plasma comes into contact with the wafer to remove material from the wafer by chemically reacting the material with an active halogen species in the gas plasma to form a gas--non-gaseous chemical reaction which produces a halide compound. In the patent, it is disclosed that this process can be utilized for sequentially removing metal such as aluminum, for removing an insulating material such as silicon dioxide, and for removing silicon. There, however, is no disclosure in the patent as to how one of several materials which could react with the gas plasma could be selectively removed with reference to the other of the materials. There is a need for a selective vapor etching process which will make this possible.